Pickup and feed unit for stacks of blanks

Abstract: A pickup and feed unit (1) for stacks (2) of blanks, wherein a movable pickup head (7) provides for successively picking up the stacks (2) off a pallet (3), on which the stacks (2) are arranged and oriented in given manner, and for feeding them to a receiving member (64). The head (7) presents a frame (29) oriented in a given manner in relation to the receiving member (64); and a pickup device (43) with suction cups (39), rotating in relation to the frame (29) and about a vertical axis (33), so that the stacks (2), once picked up, are always oriented the same way in relation to the frame (29) and the receiving member (64).

Description: The present invention relates to a pickup and feed unit for stacks of blanks. In particular, the present invention relates to a unit which may be used to advantage for successively picking up stacks of blanks off a supporting surface-normally defined by a pallet on which the stacks are placed next to one another, and arranged and oriented in known orderly manner - and feeding the stacks, with the same given orientation, to a receiving member at an unloading station. Known pickup and feed devices for stacks of blanks comprise a powered pickup head for positively engaging the stack, and which is normally guided along three perpendicular axes: two horizontal axes parallel to the stack supporting surface; and one vertical axis perpendicular to the supporting surface. EP-A-581188 discloses a pickup and feed unit for stacks of blanks arranged in a given manner on a horizontal supporting surface. The unit comprises a pickup head, which is mounted on a first fixed frame for moving in space in three different directions, and comprises a second frame having a fixed orientation in relation to the first frame and a receiving station, pickup means mounted on the second frame for rotating about a vertical axes to successively pick stacks up and off the supporting surface, and a blade which is mounted on the second frame and is movable to and from an operating position facing the pickup means for supporting a stack picked up by the pickup means. In use, the pickup head is moved in space to put the pickup means in an engagement position in relation to a stack, the pickup means are activated for picking the stack up, the blade is set in the operating position, and finally the pickup means deposit the picked up stack on the blade. If the stack has an incorrect orientation in relation to the receiving station, the pickup means are rotated about a vertical axes for setting the stack in the correct orientation prior to depositing the stack on the blade. Once the stack is deposited on the blade, the pickup head is moved to an unloading position for feeding the stack to the receiving station. If the stack is not correctly positioned on the blade, the feeding of the stack to the receiving station may result difficult and/or problems may arise for the successive utilization of the stack. It is an object of the present invention to provide a straightforward, low-cost, highly reliable pickup unit designed to overcome the aforementioned drawback. According to the present invention, there is provided a pickup and feed unit for stacks of blanks arranged in a given manner on a horizontal supporting surface; the unit comprising a pickup head, a first fixed frame on which the pickup head is mounted in a movable manner, first actuating means to move the pickup head in relation to said first frame and in space in three different directions, and a receiving member; the pickup head comprising a second frame having a fixed orientation in relation to the first frame and the receiving member, pickup means mounted on the second frame to successively pick stacks up and off said supporting surface, and a movable element which is mounted on the second frame and is movable to and from an operating position facing the pickup means for supporting a stack picked up by the pickup means; characterized in that said pickup head comprises detecting means for detecting a position of a stack on said movable element; said movable element comprising positioning means controlled by said detecting means for positioning a stack supported by the movable element in a constant predetermined position in relation to the movable element. A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a view in perspective of a preferred embodiment of the unit according to the present invention; Figure 2 shows a larger-scale side view of a detail in Figure 1; Figure 3 shows a section of the Figure 2 detail in a different operating position; Figure 4 shows a view in perspective of the Figure 3 detail; Figure 5 shows a larger-scale section along line V-V in Figure 1; Figure 6 shows a plan view of a further detail in Figure 1. Number 1 in Figure 1 indicates a unit for picking up and feeding stacks 2 arranged next to one another on a pallet 3, and each defined by a number of precut blanks 4 held together by a band (not shown). In the example shown in Figure 6, stacks 2 on pallet 3 are arranged in layers and in three parallel rows 5; and, to better exploit the space on pallet 3 as a function of the shape of blanks 4, the stacks 2 in each row 5 are rotated, in relation to stacks 2 in the other rows 5, by a given angle, normally equal to a whole multiple of 90°, about an axis perpendicular to the supporting surface P of pallet 3. As shown in Figure 1, unit 1 comprises a supporting structure 6, and a pickup head 7 traveling on structure 6 and which provides for positively engaging each stack 2. Structure 6 comprises four posts 8 arranged about pallet 3 and having respective top end portions connected by two horizontal rods 9 parallel to each other and to surface P. Rods 9 form the guide 10 of a slide 11 which comprises two sleeves 12 fitted in sliding manner to respective rods 9 and connected integral with each other by a cross member 13, and is moved along guide 10 in a horizontal direction 14 by a drive device 15 comprising, for each sleeve 12, a rack and sprocket drive (not shown) powered by a respective motor 16. Cross member 13 defines the guide of a further slide 17 to which head 7 is suspended, and which is moved in a horizontal direction 18, perpendicular to direction 14, by a drive device 19 comprising a rack and sprocket drive (not shown) powered by a respective motor 20. Head 7 is connected to slide 17 by a vertical rod 21 extending downwards through an appendix on slide 17, and movable axially, in relation to slide 17 and by a drive and guide device 22, in a vertical direction 23 perpendicular to directions 14 and 18. As shown particularly in Figure 5, device 22 comprises a pair of guide rollers 24 located on either side of rod 21 and connected in rotary manner to slide 17; and a rack and sprocket drive 25 in turn comprising a rack 26 connected integral with a lateral surface of rod 21, and a sprocket 27 meshing with rack 26 and fitted to the output shaft of a motor 28 on slide 17. As shown in Figures 2, 3 and 4, head 7 comprises a frame 20 oriented in a direction parallel to direction 14, and in turn comprising a tubular body 30 connected integral with the bottom end portion of rod 21 and housing the top end portion 31 of a substantially cylindrical body 32 having an axis 33 parallel to direction 23. Body 32 also comprises a bottom end portion 34 extending outwards of body 30 and larger in diameter than portion 31; and portion 31 is connected to body 30 in axially-fixed manner and so as to rotate about axis 33 by means of two axial bearings 35 and a radial bearing 36 gripped against portion 34 by a ring nut 37 screwed onto the top end portion of portion 31. The bottom end of portion 34 is fitted integral with a plate 38 forming part of frame 29 and in turn fitted with four suction cups 39 for positively engaging the band (not shown) of stack 2 for pickup. More specifically, each suction cup 39 is connected to plate 38 by a hollow rod 40, one end portion of which is fitted integral with respective suction cup 39, and the opposite end portion of which engages in axially-sliding manner a respective sleeve integral with plate 38. Each suction cup 39 is maintained a given distance from plate 38 by a respective reaction spring 41 fitted onto respective rod 40, and communicates with a known suction device 42 of which rod 40 forms the end portion. Body 32 and suction cups 39 constitute a pickup device 43 rotated about axis 33 and in relation to frame 29 by a gear drive 44 comprising two gears 45 meshing with each other, and one of which is fitted to portion 31, between ring nut 37 and adjacent bearing 35, while the other is fitted to the output shaft of a motor 46 and housed in a fixed support casing 47 integral with body 32 and forming part of frame 29. The angular position of body 32, and hence suction cups 39, in relation to frame 29 is detected by means of a detecting device 48 comprising an indexed annular body 49 integral with portion 34 and having four radial notches 50 equally spaced about its outer periphery; and a sensor 51 for detecting notches 50 and cooperating with a known control system (not shown). Frame 29 also comprises a plate 52 connected integral with body 30, and projecting from body 30, perpendicular to axis 33, to support sensor 51 facing body 49. On surface 53 facing suction cups 39, plate 52 is also fitted with a fork 54 for supporting stack 2 engaged by suction cups 39. Fork 54 is L-shaped, and comprises a substantially rectangular plate 55 for supporting stack 2; and an upright 56, one end of which is connected integral with plate 55, and the opposite end of which is hinged by a pin 57 to a bracket integral with surface 53, so as to rotate, in relation to plate 52, about an axis 58 perpendicular to axis 33. Fork 54 forms part of frame 29, and is rotated about axis 58, by a linear actuator 59 interposed between plate 52 and upright 56, between an operating position (Figure 2) wherein plate 55 extends facing suction cups 39, and an idle position (Figure 3) wherein plate 55 extends to the side of suction cups 39. Fork 54 presents a positioning element 60 comprising a head 61 projecting outwards of upright 56 and cooperating with a lateral surface of stack 2 engaged by pickup device 43, so as to position the stack correctly on plate 55 as determined by a further sensor 62 fitted through plate 52. As shown in Figure 1, device 1 comprises a transfer unit 63 for receiving from head 7 a stack 2 supported on fork 54 and retained by suction cups 39, and transferring stack 2 to a user machine (not shown). More specifically, unit 63 comprises a receiving member 64 consisting of a substantially parallelepiped pocket element sized to house stack 2 and open at the top and on the side facing head 7. Member 64 is oriented in a direction parallel to direction 14, and comprises a U-shaped lateral wall 65 open on the side facing frame 29; and a bottom wall defined by two horizontal plates 66 parallel to each other and separated by a distance, measured in a direction parallel to direction 18, greater than the width of plate 55 measured in the same direction. Member 64 is moved in a direction parallel to direction 18 by a drive device 67 comprising a guide defined by a rod 68 connected integral with one of rods 9 and parallel to cross member 13; and a slide 69 moved along rod 68 by a rack and sprocket drive (not shown) powered by a motor 70. Member 64 is connected to slide 69 by a vertical supporting rod 71 which presents a bottom end portion connected integral with wall 65, and is connected to slide 69 so as to move axially in relation to it by virtue of a rack and sprocket drive (not shown) powered by a motor 72. Operation of unit 1 will now be described as of the condition in which pallet 3 is located in a predetermined position between posts 8; stacks 2 of blanks 4 are arranged on pallet 3 in predetermined positions, with blanks 4 oriented in predetermined manner; a known control system (not shown) is set to control motors 16, 20, 28, 46 as a function of the position, known to the control system, of pallet 3, and as a function of the arrangement, also known to the control system, of stacks 2 on pallet 3; head 7 is raised over stacks 2; and fork 54 of head 7 is set to the idle position. As of the above condition, to pick up, for example, a stack 2a located in middle row 5 (Figures 1 and 6) and oriented the same way, on pallet 3, as required for loading onto receiving member 64, the control system (not shown) first moves head 7 over stack 2a by operating motors 16 and 20 so as to align axis 33 with a known axis 33a of stack 2a (Figure 6), and then operates motor 28 and suction device 42 so as to move head 7 towards stack 2a and positively engage stack 2a with suction cups 39. At this point, motor 28 is reversed; head 7 is raised to detach stack 2a engaged and retained by suction cups 39; actuator 59 is operated to move fork 54 into the operating position; and, at the same time, suction device 42 is deactivated to allow stack 2a to rest on plate 55 and, if necessary, be positioned correctly on plate 55 by positioning element 60. At this point, motors 16 and 20 are again operated; and stack 2a is first moved towards member 64, and then deposited inside member 64 by which it is fed in known manner to a user machine (not shown). Conversely, to pick up a stack 2b (Figures 1 and 6) located in a lateral row 5 and oriented, on pallet 3, in other than the required position for loading onto receiving member 64 (more specifically, rotated 90° anticlockwise in Figure 6), this is done in the same way as described above relative to stack 2a, except that pickup device 43 of head 7, once positioned with its axis 33 aligned with axis 33b of stack 2b, is rotated, under control of device 48, 90° anticlockwise (in Figure 6) prior to engaging stack 2b with suction cups 39, and is then rotated 90° clockwise (in Figure 6) prior to releasing stack 2b on plate 55 by deactivating suction device 42.

Claims: A pickup and feed unit for stacks (2) of blanks arranged in a given manner on a horizontal supporting surface (3); the unit comprising a pickup head (7), a first fixed frame (6) on which the pickup head (7) is mounted in a movable manner, first actuating means (16, 20, 28) to move the pickup head (7) in relation to said first frame (6) and in space in three different directions, and a receiving member (64); the pickup head (7) comprising a second frame (29) having a fixed orientation in relation to the first frame and the receiving member (64), pickup means (43) mounted on the second frame (29) to successively pick stacks (2) up and off said supporting surface (3), and a movable element (54) which is mounted on the second frame (29) and is movable to and from an operating position facing the pickup means (43) for supporting a stack (2) picked up by the pickup means (43); characterized in that said pickup head (7) comprises detecting means (62) for detecting a position of a stack (2) on said movable element (54) ; said movable element (54) comprising positioning means (60) controlled by said detecting means (62) for positioning a stack (2) supported by the movable element (54) in a constant predetermined position in relation to the movable element (54). A unit as claimed in Claim 1, characterized in that said movable element (54) is mounted for rotation about a horizontal axis (58). A unit as claimed in Claim 2, characterized in that said movable element (54) comprises a fork (54) rotating about said horizontal axis (58) and having a plate (55) for supporting a stack (2); and an actuator (59) for rotating the fork (54), about said horizontal axis (58) and in relation to said pickup means (43), to and from said operating position. A unit as claimed in any one of the foregoing Claims, characterized in that said stacks (2) arranged on said horizontal supporting surface have orientations which differ in relation to one another by a multiple, including zero, of an angle of 90° about respective axes (33a) perpendicular to the supporting surface (3); said pickup means (43) being mounted on the second frame (29) for rotating about a vertical axis (33); and said pickup head (7) further comprising second actuating means (44, 45, 46) for indexing the pickup means (43) about said vertical axis (33) through a number, including zero, of angles of 90° each, to impart each stack (2), once picked up, a constant predetermined final orientation in relation to the second frame (29) and the receiving member (64). A unit as claimed in Claim 4, characterized in that it comprises detecting means (48) for detecting the angular position of the pickup means (43) about said vertical axis (33). A unit as claimed in Claim 4 or 5, characterized in that said second frame (29) comprises a tubular first body (30) coaxial with said vertical axis (33); and said pickup means (43) comprise a second body (32) coaxial with said vertical axis (33) and engaging said first body (30) in rotary and axially-fixed manner; and drive means (46, 44) for rotating the second body (32) in relation to the first body (30) and about said vertical axis (33). A unit as claimed in any one of the foregoing Claims, characterized in that said pickup means (43) are suction cup means (39). A unit as claimed in any one of the foregoing Claims, characterized in that said receiving member (64) is movable in two different directions in relation to said first frame (6).

Inventors: MINARELLI ALESSANDRO, TACCHI ALVER, MINARELLI, ALESSANDRO, TACCHI, ALVER
Applicants: GD SPA, G.D SOCIETA' PER AZIONI
Application year: 1994
Main classification: B65G61
IPC codes: B65G61, B65G47, B65G59